update local_doc_qa.py

chains/local_doc_qa.py

 from langchain.embeddings.huggingface import HuggingFaceEmbeddings
 from langchain.vectorstores import FAISS
-from langchain.document_loaders import UnstructuredFileLoader
+from langchain.document_loaders import UnstructuredFileLoader, TextLoader
 from configs.model_config import *
 import datetime
 from textsplitter import ChineseTextSplitter
@@ -10,8 +10,7 @@ import numpy as np
 from utils import torch_gc
 from tqdm import tqdm
 from pypinyin import lazy_pinyin
-from loader import UnstructuredPaddleImageLoader
-from loader import UnstructuredPaddlePDFLoader
+from loader import UnstructuredPaddleImageLoader, UnstructuredPaddlePDFLoader
 from models.base import (BaseAnswer,
                          AnswerResult,
                          AnswerResultStream,
@@ -21,14 +20,14 @@ from models.loader import LoaderCheckPoint
 import models.shared as shared
 
 
-
 def load_file(filepath, sentence_size=SENTENCE_SIZE):
     if filepath.lower().endswith(".md"):
         loader = UnstructuredFileLoader(filepath, mode="elements")
         docs = loader.load()
     elif filepath.lower().endswith(".txt"):
-        loader = UnstructuredFileLoader(filepath, mode="elements")
-        docs = loader.load()
+        loader = TextLoader(filepath, autodetect_encoding=True)
+        textsplitter = ChineseTextSplitter(pdf=False, sentence_size=sentence_size)
+        docs = loader.load_and_split(textsplitter)
     elif filepath.lower().endswith(".pdf"):
         loader = UnstructuredPaddlePDFLoader(filepath)
         textsplitter = ChineseTextSplitter(pdf=True, sentence_size=sentence_size)